Set Operations D653A1
1. **Problem Statement:** We have three subsets of whole numbers from 1 to 20:
- $F = \{2, 4, 6, 8, 10, 12, 14, 18\}$
- $G = \{1, 2, 3, 4, 5, 7, 9, 11, 16, 18\}$
- $H = \{1, 2, 3, 5, 7, 9, 14\}$
We need to find:
(i) $F \cap G$
(ii) $(F \cup G)^c$
(iii) $(F \cap H)^c$
2. **Formulas and Rules:**
- Intersection $A \cap B$ is the set of elements common to both $A$ and $B$.
- Union $A \cup B$ is the set of elements in $A$, or $B$, or both.
- Complement $A^c$ is the set of elements not in $A$, relative to the universal set (here, whole numbers from 1 to 20).
3. **Step-by-step Solutions:**
(i) Find $F \cap G$ (elements common to both $F$ and $G$):
$F = \{2, 4, 6, 8, 10, 12, 14, 18\}$
$G = \{1, 2, 3, 4, 5, 7, 9, 11, 16, 18\}$
Common elements: $2, 4, 18$
So, $$F \cap G = \{2, 4, 18\}$$
(ii) Find $(F \cup G)^c$ (elements not in $F$ or $G$):
First find $F \cup G$:
$F \cup G = \{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18\}$
Universal set $U = \{1, 2, 3, ..., 20\}$
Elements not in $F \cup G$ are those in $U$ but not in $F \cup G$:
$\{13, 15, 17, 19, 20\}$
So, $$(F \cup G)^c = \{13, 15, 17, 19, 20\}$$
(iii) Find $(F \cap H)^c$ (elements not in both $F$ and $H$):
First find $F \cap H$:
$F = \{2, 4, 6, 8, 10, 12, 14, 18\}$
$H = \{1, 2, 3, 5, 7, 9, 14\}$
Common elements: $2, 14$
So, $$F \cap H = \{2, 14\}$$
Now find complement relative to $U$:
$$(F \cap H)^c = U - \{2, 14\} = \{1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20\}$$
**Final answers:**
(i) $F \cap G = \{2, 4, 18\}$
(ii) $(F \cup G)^c = \{13, 15, 17, 19, 20\}$
(iii) $(F \cap H)^c = \{1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20\}$
These results can be visualized on a Venn diagram with three overlapping circles representing $F$, $G$, and $H$ within the universal set of numbers 1 to 20.